Conventionally, for example, a marker or a sensor is provided at a concrete product or structure or the like and then an existing stress is measured to obtain a measurement of an internal stress in the concrete (as disclosed in Patent Document 1) or an internal stress in a concrete product or structure or the like is estimated based on the rebound amount or the AE Kaiser effect of a core extracted from the concrete (as disclosed in Patent Documents 2 and 3).
Patent Document 1: Japanese Patent Application Publication No. 2004-101322
Patent Document 2: Japanese Patent Application Publication No. 11-295198
Patent Document 3: Japanese Patent Application Publication No. 07-63624